Coordination functionalization of graphene oxide with tetraazamacrocyclic complexes of nickel(II): Generation of paramagnetic centers

摘要: Abstract We describe a novel approach to functionalization of graphene oxide (GO) which allows for facile generation paramagnetic centers from two diamagnetic components. Coordination attachment [Ni(cyclam)] 2+ or [Ni(tet b )] tetraazamacrocyclic cations carboxylic groups GO takes place under basic conditions in aqueous-based reaction medium. The procedure is very straightforward and does not require high temperatures other harsh conditions. Changing the coordination geometry Ni(II) square-planar tetracoordinated pseudooctahedral hexacoordinated brings about conversion low-spin high-spin state metal centers. Even though content complexes functionalized samples was found be relatively low (nickel ca. 1 wt%, as determined by thermogravimetric analysis, elemental analysis energy dispersive X-ray spectroscopy), room temperature magnetic susceptibility measurements easily detected appearance properties GO + [Ni(cyclam)] GO + [Ni(tet nanohybrids, with effective moments 1.95 BM 2.2 for, respectively. According density functional theory calculations, main spin localized at macrocyclic complexes, without considerable extension sheet, suggests insignificant ferromagnetic coupling agreement results measurements. tetraazamacrocycles changes Fourier-transform infrared photoelectron spectra, well morphology, observed scanning transmission electron microscopy, atomic force tunneling microscopy.